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The VR seems to work as it should and the battery is charging properly. However, I have noticed that the ammeter needle seems to vibrate - not a lot, but it's definitely moving back & forth around 1/8". I checked all the connections, and everything seems to be good.

No, it wasn't. I'm wondering if there is something about the solid sate VR that isn't playing nice with the ammeter.

Right now my plan is to, in the spring:1) Try a NOS mechanical VR that I have (date code very close to my original).2) Try a solid state VR715 "as-is".

I would really prefer to stay with a solid state unit, so if 2) fixes the vibration then I will put those 'guts' into my existing VR and see what happens. If the needle still vibrates with 2), then I'll install my NOS unit. If the needle continues to vibrate, then I guess I will need to triple-check all my connections & grounds.

The solid state VR should have nothing to do except turn charging on and off on a as needed basis. Since the gauge is wired between the main bus on the Horn Relay and the main junction block I would clean up all those connections and grounds and see if it goes away. If not run your multi-meter across your battery and see if you have any storage issues - bad cell or other issue there.

It's a brand new battery - no charging or storage issues at all as tested with a multi-meter.

I'll give all the connections another once-over this winter.

I only noticed the issue after the installation of the solid state VR. So, I figured that the way the solid state VR turns charging on& off is different than the old mechanical VR, possibly causing the vibrating ammeter needle.

I would try another known good battery, maybe one from a daily driver, before discounting the VR reg.Ensure the ground strap from the mounting bolt of the mech VR is also in place with the new VR.Might even try a separate ground strap from the new VR chassis to the alt case for an experiment.

UPDATE:I replaced the factory ammeter with a voltmeter. I noticed that the voltmeter gauge needle pulses between 13V and 15V when driving and continues to pulse when I let the vehicle idle. The pulse from 13 to 15 back to 13V takes about 2 seconds. I can hear the alternator cycling between being loaded and and not charging (that faint whine it makes when under load). As soon as I apply a load at idle (turn on headlights), it steadies out to about 14V and stays there regardless of load or rpm. However, as soon as I take it for a ride it starts pulsing again.

So, I installed a NOS Delco 515 voltage regulator (dated in 1968). Hooked it up, and it seems much 'smoother' than the solid state wells VR715. The voltmeter needle still moves between about 13V and 15V during normal driving, but it doesn't seem to pulse like the solid state unit did.

I guess I'll just leave the old Delco unit in there. Anyone see any reason not to use it?

I would suspect that the Alternator is a the real issue. The SS regulator make thousands of checks a second where the mechanical is by nature less immediate and slower to make charging decisions. If it were mine I would have the Alternator bench tested if you are sure the battery is also ok. If you haven't swapped it out as suggested by Everett I would do that first. If you need some help you know where I am

I'll try to find somewhere that can bench test the alternator. It's the original alternator, and it was rebuilt & tested about 10-12 years ago (I believe that it only needed new bearings & brushes). However, it only has a few hundred miles of use on it.

I did the tests for the diodes as outlined in the factory service manual. All tests failed. Interesting - I must be doing something wrong.

The alternator has "1D20" stamped on the top. Can I still get parts for this? Is there anyone who specializes in testing/rebuilding these things?

The alternator still seems to charge fine - it doesn't go outside of the limits as specified in the manual.

One more thing-What is the purpose of the capacitor mounted to the voltage regulator? I don't see anything in the manual about checking it or if it has any impact whatsoever on the function of the regulator. Is it noise suppression only?

I'll work backwards...the capacitor was for vehicles with optional radio. It cut the noise of the mechanical regulator in AM static. The Wells/Airtek Solid State preserved the port to hook it up for those folks who also installed their high-hat mechanical Voltage Regulator covers on the new units.

Most of the AutoZones in our area can test the Alternator. There was a guy in Farmington or maybe Canton that rebuilt GM alternators in the late 90's I'll have to see if I still have his name. But they can be rebuilt and I think there is a thread or two here on brushes and such. The Diodes are also replaceable.

There was a guy in Farmington or maybe Canton that rebuilt GM alternators in the late 90's I'll have to see if I still have his name. But they can be rebuilt and I think there is a thread or two here on brushes and such. The Diodes are also replaceable.

DJ's Alternator and Starter in Harwinton, CT is another one. I take all my alts and starters to him. He's been in business for decades and does excellent work.

There was a procedure in the service manual. You test resistance in one direction, then switch leads and check it in the other. It only said that resistance should be high in one direction and low in the other. But, if I had a bad diode then I should see reduced alternator output. The alternator appears to have no problem keeping up with load.

I spent last night taking apart & cleaning every connection I could get to, including all grounds and positive connections at the distribution block & alternator. While none of them looked particularly bad, they didn't look all that great.

After sitting for 2 days, battery voltage is right at 12.6V, which is perfect. I turned on the lights for a little bit, and the battery was right back at 12.6V after shutting them off. While just a basic test, I would expect to see less than 12.6V if the battery were bad.

I ordered another Wells VR715, and I will try installing as-is (not swapping the guts into my original VR). I'm going to pay very close attention to the ground at the VR - I was even thinking of running a dedicated ground directly from the battery cable to the VR. If that doesn't help, I'll try to go to DJ's and have him check out my alternator.

Yes you have to follow the little piece of paper exactly, mount it and make sure it has a ground before you connect it. I fried a few not checking the path to ground on new paint. 69's Voltage Regulators didn't use a ground lead they grounded to body, but if I'm remembering right both 67 & 68 VR's had rubber feet so they used a ground lead. Can't hurt to double ground her before connecting the harness. Is this still the original battery from your original thread where you lost the connection, battery died, you reconnected it but the mechanical VR over charged it? If so I still suspect you have a damaged or dead cell which could be causing your vibrating issue. If you have triple A they can run a through battery test for you or you can buy a ok unit at Harbor Freight to identify if you have cell damage. Or just pull a battery from your fleet vehicle and see if the issue goes away.